


Creosotes and Creosoting 



A Discussion of Oils and Methods from a 

Practical Viewpoint, with Some Examples 

from Experience of Difficulties Encountered 

in Obtaining Satisfactory Results 



CAPTAIN John C. Oakes 

Corps of Engineers, U.S.A. 




Reprinted from Profe^ /Nal Memoirs, Engineer Bureau, U.S.A. 
/ April-June, 1909 



By J!r&&i£ov, 
6 My '09 



x>---' 



CREOSOTES AND CREOSOTING 

BY 

Captain John C. Cakes, 

Corps of Engineers 



The use of creosote for the preservation of timber is daily becoming of 
more importance as the scarcity and cost of timber increases. There are 
many methods of treating timber with creosote, all of more or less value 
according to circumstances, but the one known as the "Bethel dead oil of 
coal tar process," or the 'Pressure process," is of greatest value and is the 
one generally meant when the term 'creosoting" is used. 

Other creosoting methods are generally designated by some descriptive 
words, as "Open tank," "Brush," "Rueping process," etc. 

RUEPING PROCESS. 

This last mentioned process is, I believe, named after its inventor. It 
is recommended for light treatment only, and its value is up to the present 
time unknown. It should, how^ever, have some value, and experiments 
now being carried on in various parts of the country, notably by the Santa 
Fe Railroad Company in connection with the protection of railroad ties, 
should soon give us data to base conclusions upon. It is described now, 
because it will be mentioned at times during the following discussion. 
This process consists of taking seasoned timber, subjecting it to an air 
pressure of some 40 pounds per square inch, and while the pressure is 
maintained, allowing the entrance into the tank of the hot creosote and 
then increasing the pressure to a sufficient degree until the required pene- 
tration is obtained. About 15 pounds per cubic foot can be forced into 
pine in this manner. The creosote is then drawn off and a vacuum is 
created ; the compressed air within the wood cells, acting upon the release 
of the pressure, drives out most of the oil, so that where 15 pounds per 
cubic foot may have been injected, after the oil has been driven out by 
the compressed air, it will be found that only from 2 to 5 pounds of oil 
have remained in the timber. 



With timber of small dimensions thorough penetration has been 
obtained by the above method, and it is claimed that the strength of the 
timber has been increased rather than diminished, owing perhaps to the 
fact that the wood cells have each received a thin coating of creosote, 
which, upon drying, may act to strengthen the cell walls. So far as is 
known, timber treated by this latter method has not been experimented 
with in marine work, but it is almost certain that it would not resist the 
teredo. It is doubtful to my mind if the process has very great preserv- 
ative value when used for timber to be exposed to the elements, because 
of the porous and spongy condition of the timber after treatment. It is 
being used by the Santa Fe Railroad Company in the treatment of their 
ties. Sufficient time, however, has not elapsed since they began its use 
to show definite results. 

Another point unfavorable to this process is that the timber being cold 
and the oil hot, or at least warm, a portion of the heavy constituents of the 
oil are crystallized or coagulated and remain in the wood. For this reason, 
principally, the Santa Fe Railroad uses the German oil, which is deficient in 
naphthalene and therefore loses less by crystallization than would other 
oils. After each treatment the oil becomes less and less a preservative for 
this reason, and besides it is adulterated by the sap, resin, etc., withdrawn 
from the timber. 

"It is argued that inasmuch as the timber is not steamed, the hot oil 
dissolves and liquifies the natural substances of the wood — i. e., resin, sap, 
etc. — and in drawing the air and oil out, when the vacuum pump is 
applied the excess oil is necessarily greatly adulterated, and its preservative 
qualities impoverished, and after this emulsion is used over and over a few 
times, while it may have the semblance of creosote, it is no longer a timber 
preservative. It will be seen that timber treated with an emulsion of 
creosote, sap, resin, and water, with a great proportion of the preservative 
qualities of the creosote lost, through evaporation and volatilization, by 
reason of frequent reheating of the emulsion, will not endure much longer 
than timber in its green state." 

For these reasons plants using this process are liable to have an adul- 
terated oil in their tanks. 

BETHEL PROCESS. 

The "Bethel" process is the one of particular interest at the present 
time in connection with marine construction, and is the one to which the 
following statements apply unless otherwise indicated. If proper care is 
exercised in treating timber by this method, the strength of the fiber of the 
wood will be practically unimpaired, and the life of same prolonged from 
fifteen to fifty years, according to the amount and quality of oil injected 



t 



and the uses to which the timber is put. It is the only commercially 
practical method by which timber may be protected against the teredo, 
and the amount required to be injected for this purpose at a given locality 
has in general depended upon the activity of the teredo at that locality. 
It has ranged from 8 or 10 pounds per cubic foot for northern waters to 
24 pounds for south Atlantic and Gulf waters, the proper requirement for 
any harbor generally being determined by experience in that harbor or the 
near vicinity. When heavy treatment is attempted the operation requires 
judgment and care, and it is owing to lack of such judgment and care that 
the result oftentimes leaves much to be desired. There seem to be no 
standard specifications covering the mechanical process among engineers or 
the firms engaged in this business, and there are no standard specifications 
in general use for creosote. 

Besides the unsatisfactory results which may arise from accident, lack 
of judgment or ignorance, there are also those from improper treatment 
intentionally given. A manufacturer who buys the best oil and does, in my 
opinion, give the timber the best of treatment, says in a published circular: 

" Unfortunately for the conscientious manufacturer, there are many in 
the creosoting business whose sole object is to make as much money as 
possible, giving as little in return as they dare. , In order to save time, and 
practically double the capacity of the plant, by running two charges through 
the cylinder in the time necessary to properly treat one, the unscrupulous 
will subject the charge to excessive steaming, with superheated steam, 
thereby destroying the fiber of the wood, and in reality defeating the object 
of creosoting, by destroying the timber instead of preserving same. Others, 
taking advantage of their customers' ignorance of creosoting, will fail to 
inject sufficient oil into the wood, relying on the fact that the product, 
being costly, will not be cut up to ascertain its condition. These are the 
'tricks of the trade' which work a hardship on the conscientious manu- 
facturer, who, when requested to bid on certain work, wnll base his figures 
on full and proper treatment, whereas some of his competitors may, and 
in many cases do, not propose to furnish the material according to speci- 
fications, thereby securing the business at a lower figure than others can 
afford to quote, and. as creosoted material all looks alike on the outside, 
they have no difficulty in passing their inferior products. The fact that 
many users of creosoted material seem to think that their advantage lies in 
beating' the manufacturers down in price puts a premium on this prac- 
tice. If they would ascertain for themselves that the oil used was the 
best, and then appoint a qualified inspector to see that they received all 
they were entitled to, both oil and method of treatment, they would be 
really doing something worth while; for what are a few dollars per M. 
feet saved in price compared with possibly double the life of the timber 
when properly treated?" 

As a result of the use of oils of different preservative value, and of treat- 
ments of varying thoroughness, it is natural that the results should vary 



greatly, and it is probable that most cases of failure of creosoted timber in 
marine, or even other work, have been caused by deficiencies of oil or of 
treatment, or both. The ordinary causes of failure are : insufficient oil ; 
poor oil, either a thin creosote or an adulterated oil; faulty mechanical 
process, as lack of seasoning, improper steaming, with reference to time or 
temperature, or both ; leaking valves ; shortening time of process, or endeav- 
oring to treat unsuitable timber. Most cases are due to insufficient oil, 
poor oil, or overheating the timber. If the steaming is not sufficient, the 
oil can not be injected; if the valves leak, the oil is not injected. Well 
seasoned and fresh green timber can not properly be treated in same charge. 

A creosote oil that contains a large proportion of soluble or volatile 
ingredients (that is, speaking generally, those that distil over at low tem- 
peratures) is unsuitable, because those ingredients are soon lost from the 
timber. Specifications should be adopted that will prevent the use of such 
creosote or adulterated oils. 

Ordinarily, specifications will require the best obtainable creosote oil and 
the injection of a definite number of pounds per cubic foot. The usual 
method of determining whether specifications have been followed is to 
place an inspector at the works to watch operations, and the inspector 
employed often has little or no knowledge of chemistry and is not suffi- 
ciently expert to determine the quality of the oil or the value of the treat- 
ment given. It is probable that there have been large quantities of 
creosoted lumber turned out from various plants under specifications for 
heavy treatment that have not received anywhere near the specified treat- 
ment. Although most engineers have heard such complaints, it is a sub- 
ject that has been investigated little, and, in my opinion, not sufficient 
attention has been given by engineers to seeing that their specifications 
have been complied with in all respects, 

OPERATION. 

The actual operation of. injecting the creosote is divided into three parts : 
the steaming of the timber to dissolve and evaporate the contents of the 
wood cells; the application of a vacuum to empty the wood cells by draw- 
ing off the sap and resinous substances, and the injection of the creosote 
under pressure. 

For light treatments air seasoning or hot-air seasoning may be substituted 
for the steaming process, but in general for a treatment of 14 pounds per 
cubic foot or more the timber is steamed. Besides facilitating the removal 
of the contents of the wood cells, the steaming, if carried far enough to 
raise the temperature of the timber throughout above 100° C, sterilizes it 



and prevents absolutely any deterioration of the timber by rot as long as 
the outside cells are filled by the antiseptic oil. 

As protection against the teredo it is probable that the creosote acts 
merely mechanically, as it seems the teredo does not bore the wood for food, 
but rather for a home in which to grow and be protected. Its food is 
thought to consist wholly of infusoria, which are not obtained from the 
wood itself. Creosote is to the teredo a disagreeable and possibly poison- 
ous substance in which he will not or can not live. Therefore, where the 
teredo is active and the waters warm, heavily-treated timber must be used 
with the object of providing an excess of oil which will during a long 
period remain within the cellular structure of the timber. The amount 
of creosote per cubic foot commonly required in the waters of the Gulf of 
Mexico is 20 to 24 pounds. In Louisiana, Alabama, and Mississippi 20 
pounds is the heaviest treatment usually required. Engineers in charge of 
some of the plants say they can not inject more than that amount without 
steaming at a higher pressure than 35 pounds. This may be correct with 
reference to some kinds of pine, but I do not believe it is. 

On the Texas coast 24 pounds is almost invariably required for pine 
timber, and the Galveston Wharf Co. is now asking for 27 pounds, or 
what is practically complete saturation. I have known of several cases 
where over 26 pounds per cubic foot have been injected. The statement 
has often been made that it is impossible to thoroughly penetrate long-leaf 
pine. This statement is not correct. Very recently we had occasion to 
specify 24-pound treatment for wharf timbers of selected long-leaf heart 
pine, showing not more than 1 inch of sapwood on one side of any timber. 
This timber received 25.3 pounds per cubic foot without any apparent 
injury to the timber and showed thorough penetration throughout. 

The operation of injecting this amount of oil into timber is practically 
as follows: The timber is run into the treating cylinder; after the doors 
are closed, live steam is admitted at a pressure generally of from 30 to 45 
pounds per square inch and the steaming is carried on from eight to forty 
hours, the exact time depending upon the individual opinion of the operator, 
as well as upon the moisture content of the rimber, the amount of oil to 
be injected, the size of the timber under treatment, its hardness and com- 
pactness, etc. In some cases the steam pressure is allowed to go above 45 
pounds, but there is constant risk of injuring the strength of the timber 
and the pressure must be watched carefully. By watching the drainage 
of the cylinders an operator of experience can tell by the color, consistency, 
etc., of the fluid drained off when the timber is being injured. 

Timber that has been steamed at a pressure of over 35 pounds should 
be under suspicion and the pieces tested by dropping or subjecting them 



to bending strains to see that the timber is not "cooked," Even when 
subjected to pressures under 35 pounds damage is sometimes done. The 
injury seems to be of several kinds; the cell walls may be broken down 
by expansion due to the creation of steam from the sap and water in the 
cells or they may be charred by too great heat long continued, or they 
may be broken down by too long boiling. 

When the steam is at last blown out of the cylinder, the vacuum pumps 
are started and as much of the air, water, sap and resinous substances as 
possible is exhausted from the cylinder and from the wood structure. 
The vacuum is usually held for from two to six hours, at from 17 to 26 
inches. Finally, the preservative is run into the cylinder while the vacuum 
is held as far as possible until the timber is covered by the oil and the 
pressure pumps are started and continued until the desired amount of oil 
is forced into the wood. The amount is generally determined by measure- 
ments on the storage tank. Upon completion of the treatment the surplus 
oil is returned to the storage tanks, the timber is allowed to drip for a few 
minutes, the cylinder doors are opened, and the treated timber is withdrawn. 

The process itself as described appears to be a simple one, but there are 
many things that may be done or left undone which will affect materially 
the finished product. 

CREOSOTE OIL. 

Before proceeding further it will be necessary to discuss the subject of 
creosote oil. 

One of the by-products of the manufacture of coal gas is coal tar, a very 
important one on account of the numerous and valuable chemicals obtained 
therefrom, among which are ammonia, carbolic acid, coal-tar dyes, creo- 
sote, etc.: 

When coal tar is distilled "water passes over holding salts of ammonia 
in solution and accompanied by a brown, oily, offensive liquid, which 
collects upon the surface of the water. This is a mixture of the hydro- 
carbons which are lighter than water, viz., benzene, toluene, xylene, and 
isocumene. * * ''^ As the distillation proceeds and the temperature 
rises a yellow oil distils over, which is heavier than water and sinks in the 
receiver. This oil, commonly called 'dead oil,' is much more abundant 
than the light oils and amounts to about one-fourth of the weight of the 
tar and contains those constituents of tar which have a high specific gravity 
and boiling point, particularly naphthalene, aniline, quinoline and carbolic 
acid. The proportion of naphthalene in this oil increases with the pro- 
gress of the distillation, as would be expected from its high boiling point, so 
that the last portions of the oil which distil over become nearly solid on 
cooling. When this is the case, the distillation is generally stopped, a 



black viscous residue is found in the retort, which constitutes pitch and is 
employed for the preparation of Brunswick black and asphalt for paving." 
(Bloxam's Chemistry, page 774.) 

This pitch is also used for other purposes, as manufacture of roofing 
paper, etc. The point at which the distillation ceased will, of course, 
determine the ingredients of both the pitch and the dead oil. 

In America there is practically no market for the hard pitch, but there 
is a market for the soft pitch for roofing. Therefore, American oils 
generally will be lighter than the English oils and will contain very little, 
if any, of the high-boiling oils. English oils, on the other hand, contain 
a large percentage of th^ heavier and higher boiling oils. 

As a result of the process of its manufacture, creosote contains various 
chemicals and in varying degrees, depending upon the quality of the tar 
and the temperature at which the distillation was terminated. After the 
extraction of the chemicals from this ' dead oil," which are commercially 
valuable, as aniline, carbolic acid, and sometimes naphthalene and anthra- 
cene, there remains the commercial oil "creosote." It will, therefore, be 
seen that the oil sold as creosote is that portion of the dead oil of coal tar 
left over after those hydrocarbons that are commercially valuable are 
taken out. Mixed with this residue or refuse oil may be other 
chemicals, which were used in the process ^f extracting some of the valu- 
able hydrocarbons. If the creosote is obtained from works where the 
carbolic acid is extracted, the oil will have a low percentage of ''tar acids." 
If naphthalene has been extracted, the oil will be low in that quality, and 
if roofing pitch has been manufactured, there will be almost no anthracene, 
because the distillation ceased before the oils containing anthracene were 
distilled over. Varying as commercial creosote oils do, their preservative 
value must also vary greatly. 

There are also other oils on the market w^iich are mixed with coal-tar 
creosote or substituted therefor, as crude petroleum, oil from Mond- 
producer tar, oil-gas tar, etc. There are many opinions as to the value of 
these oils as preservatives. / Chemists do not agree as to the value of the 
various oils or the ingredients thereof, and engineers therefore are at a loss 
when making specifications, j 

At one time it was thought that creosote should have a large percentage 
of tar acids. A series of experiments by Mr. Coisne, an engineer of the 
Belgian Government, showed this idea was incorrect. 

'' He used samples of creosote oil containing 15 per cent, 8 per cent, and 
7 per cent of tar acids and one containing no tar acid. He impregnated 
wood shavings with these oils and placed them in a putrefying pit. After 
four years in this pit, he found that 'the results were strikingly in favor of 



8 

the heavier oils and averse to the tar acids, which last bodies appeared to 
have been wholly ineffective. The shavings which had been prepared 
with the lightest portion of the oils, although they had contained the largest 
portions of the tar acids, were, nevertheless, in the worst condition.' 
* * * Best of all were the shavings prepared with the heaviest oils, 
produced by distilling at the highest temperature, even when containing 
no tar acids; these last were all perfectly sound. Uncreosoted shavings 
were all rotten."^ 

It has also been thought that naphthalene was the most valuable pre- 
servative constituent of creosote. The adherents of the "naphthalene 
theory " claim that the protection is gained by the volatilization of the 
lighter oils which disinfect the water that enters the wood, and thereby 
kill the micro-organisms that would otherwise find a lodging, and that a 
heavy oil would not do this so readily. They cite the fact that the oil 
now found in wood well preserved for many years is lacking in light oils 
(and naphthalene) and contend that the very loss of them is what has pro- 
tected the timber. Many experiments have been made to determine the 
truth of this, but the results have not been definite, and it is still a disptited 
question. Some firms and corporations specify a definite amount of 
naphthalene, because oils that have been proven successful with them had 
that amount. It is doubtful, however, if the requirement that there shall 
be a definite amount of naphthalene in the oil does not result in obtaining 
a poor oil. It is certain that naphthalene volatilizes easily, and sometimes 
after only a few days timber impregnated with a creosote rich in naphtha- 
lene and protected against air currents will be covered wnth a white frost- 
ing of naphthalene crystals, which when exposed to the elements rapidly 
disappear. Certainly that portion of this ingredient that crystallizes on the 
outside of the timber is of no use. 

Some people claim that the crystalline naphthalene acts as a stopper in 
the wood cells to hold the liquid in. I do not believe this, for I have 
found that oils high in naphthalene dry out of the timbers rapidly, while 
oils having a large portion of the high-boiling constituents remain in a 
long time, due to the solidifying of the. heavy oil in the outside cells and 
the deposit of pitch over the surface of the timber. 

The analysis of some forty specimens of creosoted timber that had 
successfully resisted the elements and marine borers for a number of years, 
made by Prof. Gellert Alleman and published in Circular No. 98, Forest 
Service, Department of Agriculture, show that of the ingredients remain- 
ing in the timber the anthracene and higher boiling oils represented the 
largest percentage. It is logical that this should be so, because the lower 
boiling oils are the readiest to volatilize and disappear. 

*"Changes in Creosote During Exposure," by V^on Schrenk, Fulk and Kanimerer. 



The opinion is becoming more prevalent that the higher boiling oils are 
the important ones ; the '' trade " considers as best those creosotes containing 
the high-boiling oils with a large percentage of anthracene. 

The idea that naphthalene is the most important ingredient in the oil 
has been, however, very prevalent, and that idea has led to the requirement 
in specifications that a large percentage of naphthalene should be present. 
Some specifications require as high as 40 per cent. 

In a case that has recently come under my observation the oil used was 
not what is considered by the trade as a first-class creosote oil, and, on 
objection being made to it, the firm replied that they had to buy that 
quality of oil in order to comply with certain specifications, and showed 
several, some of them Government specifications, that did practically 
require an oil like the one in question. One case is known where an oil 
was rejected because it had not sufficient naphthalene. The oil was 
undoubtedly a poor oil, but should, in my opinion, have been rejected for 
other reasons. One Government specification at hand allows 25 per cent 
to be distilled over below 210 C. and does not designate the inferior 
limit, but, 1 suppose, 170° C. would be understood. Another specification 
at hand requires 8 to 10 per cent distillate below 200° C, exclusive of water. 

In my opinion, that portion of the oil that distils over below 210° C, 
and certainly below 200° C, is lost from the timber very soon after it is 
removed from the cylinder and, consequently, to require any proportion 
of the oil to distil over below 200° C. is to require that just that proportion 
be furnished in order that same may be immediately lost. The require- 
ments mentioned above could not have been complied with by what is 
considered as a first-class creosote oil. The best English creosote oils 
will not comply with those requirements, and in consequence American 
oils which are deficient in high-boiling constituents or foreign adulterated 
oils would have to be furnished. 

The Forest Service has published Circular No. 112, "The Analysis and 
Grading of Creosotes," which is of particular interest in this connection, 
and to which the readers of these remarks are referred for more technical 
information. 

DISTILLATION. 

In most specifications the composition of the oil is specified in one of 
two ways, viz., by designating the percentage of certain compounds, or 
by specifying the percentages of distillates, between certain temperatures. 

In using this latter method the manner in which the distillation is to be 
made must always be designated, because analysis of the same oil by different 
chemists, or even by the same chemists, will show greatly varying results, 
owing to the different methods and different apparatus employed. To 



10 

illustrate this point, the following analyses of the same sample by the same 
chemist are cited : 

''The oil was distilled according to two methods: Analysis No. 1, 
according to the standard method of analysis adopted by the American 
Railway Engineering and Maintenance of Way Association ; Analysis 
No. 2, according to the English method of analysis as used by Messrs. 
Burt, Boulton & Haywood. 

Analysis No. 1. Percent 

Below 210= C 1.6 

210^ C. to 235 C 18.8 

235 to 270 35.9 

270 to315 14.2 

315 to355 17.7 

Residue 10.9 

Analysis No. 2. Per cent 

Below 210 C. 0.5 

210 C. to 235 C : 2.3 

235 to270 37.2 

270 to315 21.8 

Residue 38.2 

It will be noted that the English method of analysis shows a higher 
percentage of the high-boiling oils than the other method. This must be 
remembered in studying data relating to creosotes. 

ERRORS. 
With reference to ordinary errors that may occur during the chemical 
process, the following is quoted from Circular No. 80, Forest Service : 

''There are three sources of error which are likely to cause material 
difference in analyses made by different workers. 

"1. The accuracy of thermometers, even high-priced ones, is prob- 
lematical. One of the thermometers used in the experiments reported, the 
list price of which was $10.00, showed errors ranging from 1.4° at 200° 
to 6° at 500°. A cheaper, nitrogen-filled thermometer showed a rise in 
the zero point of 23° after being heated to a high temperature. When 
using thermometers for high temperature work it is necessary, therefore, 
that great care be exercised to insure their accuracy. 

"2. The readings of the thermometer are too low on account of the 
emergent thermometer stem being at a lower temperature than the portion 
in the vapor. On the thermometers which were used in the experiments 
detailed above this correction amounts to about 2.3° at 240°, and about 
8° at 360° C. No corrections for the emergent thermometer stem have 
been made, since such corrections are not ordinarily made in creosote 
analyses. It is probable that the amount of this correction would be 
nearly the same for the thermometers used by different analysts, so that 
no great variation in results should come from this source. 

"3. It is very essential that a creosote sample be absolutel\' liquid 
before the quantity used for distillation is weighed out, since a small 
amount of unliquified naphthalene will produce an appreciable error in the 
results of the distilhition. It is not at all improbable that the samples sent 



11 

to the laboratory for analysis may not represent the average composition 
of the creosote under examination, and this may or may not be under the 
control of the analyst, but it is possible for him to obtain a perfectly 
representative sample of the oil which is brought into the laboratory. 

VARYING METHODS IN USE. 

Besides the errors mentioned above it has been found that different 
results are obtained due to the shape and capacity of the vessel used in dis- 
tilling the oil ; the rate at which the distillation takes place; and last, but 
most important of all, the position of the thermometer bulb, whether in 
the oil, just above the oil, or just below the outlet tube. 

The method common in England is to place the thermometer directly 
in the oil, generally one-fourth inch or one-eighth inch from the bottom 
of the flask. In this country it is sometimes specified that the bulb of the 
thermometer shall be one-fourth or one-half inch above the liquid. To 
show how important the position of the bulb of the thermometer is, the 
following tables are copied from a published article entitled, ''Standard 
Method for Analysis of Coal-tar Creosote," ^ by Dr. Hermann Von 
Schrenk, E. B. Fulks and A. L. Kammerer. 

Table No. I.— Influence of thermometer position, using the same retort and the 

same oil. 





Two thermometers in the retort. 


One thermometer 
in the retort. 




Bulb in oil. 


Bulb at olt-take. 


Bulb 54-inch 
above oil. 


Below 210' C 

210 C. to 240' C. 

240 C. to 355= C. 


1.75 
41.54 
50.37 

5.88 


82.54 
11.32 


11.43 
47.31 
34.35 


Residue 


5.88 


6.52 


Total 


99.74 


99.74 


99 61 







Simultaneous readings of two thermometers. 



Bulb in oil, °C. 


Bulb at off-take, ° C. 


Bulb in oil, °C. 


Bulb at off-take, ° C. 


210 


115 


290 


201 


210 


123 


300 


206 


218 


144 


310 


208 


222 


158 


315 


208 


234 


180 


318 


210 


240 


183 


330 


225 


250 


187 


342 


231 


260 


192 


350 


240 


270 


199 


355 


248 



"Bulletin No. 65, July, 1905, American Railway Engineering and Maintenance 
of Wav Association. 



12 



Table No. II. — Distillation of oil, showing comparative temperatures at which 
certain fractions distil, with the thermometer bulb in different positions. 

Distilled with two thermometers, one in the oil and one at outlet of retort, showing 
simultaneous temperatures. 





Temperature in oil. 


TerriDerature at 
off-take, ° C. 


Distillates. 


210" C. 


118 
169 
218 


Per cent. 

7 47 


235° C. 


36 65 


355' C. 


43.93 


Residue 


11.34 










Total 


99.39 









Distilled with two thermometers, one in the oil and one >^-inch above oil, showing 
simultaneous temperatures. 



Temperature in oil. 


Temperature 
H-inch above, 


Distillates. 


210' C 


199 
222 
340 


Per cent. 

1 23 


235° C. 


35 82 


343" C. 


44.05 


Residue 


12.16 










Total 


99.26 







Table No, III. — The influence of the kind of vessel used is shown in the following 

table. 

One sample of tar oil distilled under similar conditions in different vessels. 





250 cc. side neck 
distilling bulb. 


250 cc. retort. 


500 cc. retort. 


210° C. 


1.30 
50.14 
38.40 

9.48 


1.36 
48.27 
46.59 

3.35 


i .75 


210° C. to 240° C. 


41.54 


240° C. to 355° C. 


50.57 


Residue 


5.88 






Total 


99.32 


99.57 


99.74 







A study of the above tables will show conclusively how necessary it is 
when indicating an oil by its fractional distillation that the position of the 
bulb of the thermometer shall be mentioned. Many discrepancies in 
analyses by different chemists are explained, and the cause of misunder- 
standings between manufacturer and consumer becomes apparent after 
considering the above tables. The first point, therefore, to be determined 
when a report of a fractional distillation is under consideration is the posi- 
tion of the thermometer bulb with respect to the liquid. As it appears 
from the studies available that the kind of vessel, its size, the rate of dis- 



13 

tillation and the position of the thermometer affect the amount of distil- 
late passing over between any two recorded temperatures, it would seem 
to be desirable to standardize the apparatus and methods of analysis. 

As what we must have is a method that will give uniform results, and 
with the same oil the same results by all reliable chemists, it would seem 
that the thermometer should register the temperature of the vapors them- 
selves and not of the oil. Placing the bulb of the thermometer in the oil 
itself is certain to give results which vary greatly, because it will then 
register the temperature of the oil that directly surrounds the bulb, and 
not the temperature of the vapors that are passing off, nor even the gen- 
eral temperature of the liquid. If the bulb be placed just above the oil, 
the temperature recorded will be affected to a less degree by the temper- 
ature of the oil, but it still will not necessarily read the temperature of the 
gases. If it is placed at some distance above the oil, as in the method 
recommended by Prof. Gellert Alleman in Circular No. 98 of the Forest 
Service, the temperature recorded by the thermometer will be more nearly 
that of the gases passing off, and if the same oil is analyzed a number of 
times with the thermometer as noted, more uniform results will be ob- 
tained than by the other methods. I must say, furthermore, that the appa- 
ratus as described by Professor Alleman in this circular appeals to me as 
being more exact and more adapted to obtain uniform results than the 
apparatus ordinarily used. 

The only objection known to the use of the side-neck flask is that the 
liquid "pops" a great deal and often jumps from the bottom of the flask 
out through the outlet neck, even though the outlet is 6 inches above the 
liquid. This happened during many of the analyses made by the inspector 
operating under the United States Engineer Office at Galveston, Texas, 
until he covered the flask with asbestos from top to bottom. The probable 
cause of the "popping" is the condensed vapor, which on falling back 
into the oil is again vaporized almost instantly. It is very much worse 
when a quantity of water is in the oil. 

A uniform rate of distillation should also be specified, otherwise the 
analysis can be manipulated by forcing or retarding the heat. The high- 
boiling oils will volatilize at a temperature below their boiling pomt, just 
as water evaporates below 100° C, or they will not have opportunity to 
become completely volatilized at their proper temperature if the flame is 
forced. A rate of one drop per second was used in the method of analysis 
reported in Forest Service Circular No. 112, and until some other 
standard is adopted such rate is reasonable and is recommended. 

It is also important to divide the range of temperature into certain divi- 
sions, so that the distillates obtained throughout the range of a division will 



14 

have some definite similarity. Professor Alleman proposes to separate the 
distillates in a manner somewhat different from that used by other chem- 
ists, and his reasons given in the same circular mentioned above seem to 
me cogent, and his remarks so instructive, that the following are quoted: 

"When a complex mixture such as creosote is distilled, the various dis- 
tillates passing over do not volatilize at the exact boiling point of the 
individual compounds which they contain, and the compounds can not be 
separated in the pure state except by repeated distillations. If all creosote 
oils used were similarly constituted, then, by means of a series of analyses, 
it could readily be determined at what temperatures the various constit- 
uents volatilize; but since oils vary greatly in composition, this is not 
possible; such temperatures as are determined upon for the separation of 
the various fractions are, in a measure, arbitrary. For instance, if an oil 
is rich in naphthalene and also contains a certain amount of material dis- 
tilling below 200° C, some of the naphthalene is liable to volatilize with 
the lighter oil, and it will have entirely passed over when a temperature of 
245° C. is reached. On the other hand, if the oil contains a large amount 
of the higher boiling constituents, such as anthracene, and also a consider- 
able amount of naphthalene, the latter is frequently not gotten rid of before 
a temperature of 250° C. is reached. The point at which naphthalene 
ceases to come off, if it is present, can be determined by allowing a drop 
of the distillate supposed to contain it to fall on a piece of cold porcelain. 
If the drop solidifies, the presence of naphthalene is shown. 

" In over eight hundred distillations conducted by the writer it was found 
that 92 per cent of those oils which contained naphthalene gave it off be- 
tween 205° C. and 245° C, and one of the fractions has consequently 
been taken between these temperatures. 

"After conducting tests on a great many oils, the writer was of the 
opinion that the most information could be obtained by separating the 
distillates as follows: 

1. To 170° C. 

2. 170' C. to 205^ C. 

3. 205 to 245 

4. 245 to 270 

5. 270 to 320 

6. 320 to 420 

7. Residue above 420 C. 

"Fraction No. 1 contains the light oil and water. In case much water 
is present, some of the naphthalene will frequently volatilize with it. 

"No. 2 should contain phenol and the cresols (tar acids). 

"No. 3 contains naphthalene and the two methylnaphthalenes ; these 
bodies crystallize out, and by filtration the amount of solid naphthalene can 
be determined. 

"No. 4 contains, among other compounds, dimethylnaphthalenes. 

"No. 5 was usually entirely liquid on cooling, and its composition is 
complex and variable. In case little anthracene oil is present, some of it 
will be found in this distillate. 

"No. 6 usually contains anthracene oil, phcnanthrenc, acridciic, etc., 
and solidifies on cooling. 



15 

"The residue above 420° C. may contain practically the same as No. 6, 
and also tar. 

"'Tar acids' is a technical term used to denote all those creosote con- 
stituents which contain hydroxyl groups. The known compounds of this 
sort occurring in creosote are phenol or carbolic acid ; the ortho, meta, 
and para cresols, usually termed cresylic acids; A and B naphthol, and 
xylenols."* 

While I am not advocating at the present time any particular method 
of analysis and am not sufficiently versed in the chemistry of creosote to 
warrant a recommendation, I must say the above method of analysis and 
distribution of distillate intervals appeals to me. / do^ however^ advocate 
some standard method for use of the Corps of Engineers, and I think the 
subject should be taken up and such standard provided. 



SPECIFIC GRAVITY. 

Under the present methods employed, the specific gravity of creosote is 
variously specified for temperatures of 15° C, 38° C, 50° C. and 60° C, 
As most oils are not completely liquified at 15° C, and some not even at 
38° C, the gravity may be taken at any temperature, and then reduced to 
15° C, by using the coefficient .0008 for each degree centrigrade the tem- 
perature of the oil is found to be above 15° and adding the product to the 
observed gravity. "If the Fahrenheit scale is used, the factor should be 
.00044.t The objection to referring the specific gravity to 15° C. is that 
the factor is not constant for all creosotes. At 60° C. almost without 
exception, all of the fractions are liquid, and the gravity can be determined 
directly. All things considered it is thought that the specific gravity 
should be determined at 60° C. If oil at that temperature be compared 
with water of the same temperature, a more nearly correct specific gravity 
is determined. Even this is not accurate, because water and oils have 
different factors of expansion, and therefore if reduced to a temperature of 
15° C. they would not bear exactly the above relation. 

The lowest specific gravity for any fraction of a pure creosote seems to 
be about 1.01 and that for the fraction under 225° C. The lowest for 
the high fractions is about 1.07. A creosote falling within the limits of 
the distillation specified for Class A, in Forest Service Circular No. 112, 
should probably never be lower than 1.04 at 60° C. An oil having a 
specific gravity as a whole of more than 1.07 should be looked on with 
suspicion and investigated. Unless it is almost wholly lacking in the low- 

* Circular No. 98, Forest Service. 

t Authority : Von Schrenk, Fulks and Kammerer. 



16 

boiling fractions it possibly has some hard pitch or undistilled coal tar 
mixed with it. 

PRACTICAL OPERATION AT PLANT. 

Having determined by analysis that the oil to be furnished for a given 
lot of timber is satisfactory, it is important to see that it remains so. 
One of the particular points to be guarded against is the dilution of the 
oil by the addition of water. As the storage tanks at most plants 
have open tops and a quantity of water is usually required on top of the 
oil for fire protection and to prevent evaporation, the oil passing to the 
treating cylinder may easily carry water with it, particularly as the oil 
seems to draw down from the center of the tank and sucks the water 
down the funnel-shaped depression caused by the flow from the bottom 
of the tank. 

Again the oil in the storage tank must be kept heated by steam coils, else 
the heavier oils will settle to the bottom and become hard and only the light 
oils and water can be drawn off. If the steam coils leak, water is mixed 
with the oil. Dilution may also be caused by not cleaning the treating 
cylinder of condensed steam, saps and resins, obtained from the timber 
after the steaming and vacuum processes just before allowing the entrance 
of the oil; leaking of steam pipes in the treating cylinder, etc. ; or by 
using oil that has been previously used in the Rueping process, already 
described. This process deliberately mixes all of the sap and resinous 
substances from the wood with the oil. Oil used a few times in this 
process may become sadly deteriorated and not fit to be used. 

FAIR SAMPLES SHOULD BE OBTAINED. 

During the mechanical operation it is important that the inspector make 
sure that a fair sample of the oil was submitted for chemical analysis, and 
for this reason he must be able to make at least a rough analysis to ascer- 
tain whether the oil is the same previously analyzed, and, if so, that it has 
not become diluted. As creosote is a mixture of various oils having 
different specific gravities, and if stored in a tank whose contents have not 
been stirred and particularly if unheated, the oils gradually arrange them- 
selves more or less in layers according to specific gravity. The heavier 
oils at the bottom become hard, and if a portion of the oil from such a 
tank is drawn off it is very likely that only the lighter oils and water will 
be withdrawn. For this reason the oil when about to be used should be 
kept heated to about 80° C. In taking samples from a tank having con- 
siderable vertical height a vessel should be used which will enable the 
inspector to take his sample at any height, and samples from the bottom. 



17 

middle and top of the tank should be compared, and even while the injec- 
tion is taking place samples should also be tested that are drawn from the 
treating cylinder, because at every step of the process, and at every 
movement of the oil, dilution may take place. 

STEAMING. 

When steam is applied, there is a rapid condensation in the cylinder, 
due to the cooling action of the cylinder and wood. To prevent this, 
some plants use superheated steam sufficient to absorb this condensed 
water; or rather to prevent the condensation. After the condensation ceases, 
the timber gradually becomes heated and the sap is volatilized from the 
wood, as are a large part of the resinous compounds, sufficient steam being 
let into the cylinder to replace the lost heat and take up the additional 
moisture. If the timber is green and contains a large amount of sap, the 
cylinder is sometimes blown out several times during the steaming. By 
far the larger part of the sap constituent of the wood is extracted during 
the steaming process and passes off as steam and water through valves in 
the bottom of the cylinder. 

The degree of heat necessary to be used is that which is sufficient to 
volatilize the sap and resinous substances. The more sap in the wood the 
higher the pressure that can safely be used. For heavy treatment, a pres- 
sure of 20 or even 25 pounds may be insufficient to effect the desired result. 
I believe the best results are obtained by using 30 to 35 pounds pressure. 
Forty pounds may be needed for green timber, provided it is live steam. 
Superheated steam should never be used even at low pressures, except at 
the very beginning, when the timber and cylinder are cold. One creosote 
company allows a pressure of 60 pounds on all their work, irrespective of 
the required treatment. They claim to have steamed paving blocks as 
high as 80 pounds without causing deterioration sufficient to be detected, 
even under such a test as heavy traffic gives them. They evidently do not 
damage the timber or they would have modified the treatment. None of 
the other plants that I am acquainted with is able to use such heavy pres- 
sures, and I have grave doubts about the reliability of the recording instru- 
ments. The greatest damage is caused by burning or rupture of the cell 
walls, due to superheated steam or to applying the pressure too fast. If 
the material is heated slowly, there is not such great danger of rupturing 
the cell walls. A dry timber should not be steamed at as heavy pressure 
as a green timber. 

According to experience of the United States Engineer Office at Gal- 
veston, the best results are obtained by increasing the pressure slowly. 



18 

taking an hour or two to attain the maximum pressure and then gradually 
decreasing it. 

THE VACUUM. 

The action of the vacuum is perhaps the least understood of the proc- 
esses connected with creosoting. It is understood, of course, that a certain 
amount of moisture will be withdrawn, including the dissolved resins, etc., 
but it is not generally known that most of the moisture is drawn off in a 
gaseous form and that better results are obtained when the heat is kept 
up so that the moisture content of the cells may be boiled out under the 
decreased pressure. 

Mr. C. M. Davis, United States inspector under the Galveston office, 
reported as follows: 

*'The vacuum seems to volatilize the moisture left in the wood after the 
steaming process is completed, if the timber is kept heated. At Slidell, 
La., we obtained the best results by having steam in the cylinder coils 
while the vacuum was on. The vacuum seems to cause the water in the 
wood to 'boil' and vaporize very rapidly, and this vapor passed out through 
the vacuum pump. Some was, of course, left in the cylinder and was 
collected in the 'sap cylinder' underneath the treating cylinder, but the 
amount thus collected was surprisingly small. In the case of a charge of 
2,000 cubic feet of very green pine — so full of sap that it would not float 
in water — there was less than 1 pound per cubic foot collected in this 
manner out of, possibly, 25 pounds per cubic foot extracted." 

INJECTION OF OIL. 

The vacuum is generally used to accelerate the filling of the treating 
cylinder with oil. It is very important to have the cylinder filled as quickly 
as possible, in order that absorption may be as uniform as possible. By 
proper management of plant the cylinder may be filled in about ten min- 
utes without pumping, but when the arrangement is poor and pumping 
has to be resorted to it may take an hour or more. 

At most plants the method used to calculate the amount of oil to be 
injected is to measure the timber and find the amount required to be in- 
jected measured in tenths of a foot on the tank gauge. The oil is turned 
into the cylinder, and a gauge reading is taken when the overflow pipe 
from the cylinder shows it to be full. Then the number of tenths from 
the tank is injected by pressure less the amount of absorption which must 
be estimated, but which is eventually checked by a final reading of the 
tank gauge after the surplus oil is returned to the tank. This method is 
open to the objection that there is no w^ay of determining whether the esti- 
mated amount of absorption was correct or not until the process is ended. 
A better method is to use the cubical contents of the cylinder, the dis- 



19 

placement of the load and the amount to be injected. With these data 
the uncertain quantity, absorption, is disregarded. 

A close inspection of the process of injecting the oil should be made. 
Improper steaming and vacuum processes show for themselves in the 
finished product, but a deficiency of oil can not be determined without 
expensive investigation. Every source of supply of oil should be gauged 
before and after treatment. It is not unusual to have connections from 
the cylinder to several supply tanks and to one or more outlet tanks from 
which the oil is finally returned to the supply tank. No valve is free 
from the tendency to leak even under the best of management. Especially 
important is the correction to be made for change in temperature of the 
oil in the storage tank before and after treatment. Creosote oil changes 
in volume approximately 1 per cent for every 12/4° C. A thermometer 
should be attached to the side of the supply tank in such a position that 
it will not be locally affected by the steam coils, and readings taken before 
and after the operations and, the gauge readings corrected for the change 
in temperature. It is not uncommon for this to make a difference of as 
much as 4 or 5 per cent in the number of pounds injected. 

ABSORPTION. 

The amount of oil absorbed before pressure is applied depends on the 
time taken to fill the cylinder, the grain of the timber, the extent of 
seasoning and steaming and the viscosity of the oil. It never seems to 
be uniform even under seemingly the same conditions. 

In the case of the two treatments illustrated by Fig. 1, the loblolly stock 
absorbed 27}^ per cent during the fifteen minutes taken to fill the tank. 
The long-leaf timber absorbed 23 per cent in twelve minutes. The two 
charges were seasoned to about the same extent, and the absorption was 
the greatest and the most uniform I have noted, viz., about 6 pounds per 
cubic foot in each case. 

Such high percentages of absorption as this can only be obtained by 
using a very hot oil and having the timber thoroughly steamed, possibly 
oversteamed. In these cases the oil was kept at a temperature of 88°C. 
Generally the absorption is much less, and when the oil is applied at low 
temperatures, as 50°C. to 65°C., the absorption may not amount to more 
than 10 per cent. 

Only such oil as is practically free from tar acids should be applied as 
hot as 88°C., as it is thought that the tar acids affect the structure of the 
wood materially if the temperature of the oil is too high during injection. 

In the case of light treatments too great rapidity of absorption is a 



20 



serious drawback to uniform treatment of the charge. The timber at the 
bottom of the cylinder absorbs so much more than those at the top that 
it becomes very noticeable, particularly if a long time is consumed in 
filling the cylinder. When only the amount of oil is supplied to provide 
an average treatment for the charge, and the timber is seasoned, the oil 
hot, and if a long time is employed in filling the cylinder, the bottom 





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Fig. 1. Curves showing rapidity with which oil is injected into different classes of 

timber. 

timbers may have double the requisite amount and the top timbers 
practically none. 

RATE OF INJECTION AND PRESSURE. 

The accompanying curve (Fig. l) shows the relative rapidity with which 
the oil was injected into two charges of timber under contract with the Gal- 
veston Engineer Office. In the case of the long-leaf pine the percentage of 
heartwood was about 25. The sapwood was entirely penetrated in five hours, 
and evidently a large part was penetrated in about two hours, as shown by 
the abrupt break in the absorption and pressure curves. The curves 



21 

illustrate what may be called average cases, and they show the importance 
of having all of the timber in a single charge of the same density. More 
especially is this the case with light treatments, for reasons mentioned 
above. 

When different woods are combined in a charge, the less dense get 
more than was intended and the close grained less than was intended. 
Cases have been noted where long leaf and loblolly pines were included 
in the same charge, with the result that the loblolly were saturated and 
the long leaf received only 3 or 4 pounds per cubic foot and only 1 or 
1/^-inch penetration. 

EXAMPLES FROM EXPERIENCE. 

A description of a recent experience, in attempting to obtain a good 
treatment, may be of interest to others. 

The specifications for creosoted piles called for 24 pounds per cubic 
foot, the use of a good creosote oil, that the strength of the piles should 
not be impaired and that they should be protected against the teredo. 
Realizing that it would be difficult to make specifications that would be 
fair to both contractor and Government, no effort was made to specify the 
kind of oil to be used or treatment to be given other than the above, but 
an affidavit was required of the president or manager of the company 
that the specifications had been complied wnth. Upon delivery of the 
piles their appearance was noted as peculiar, the penetration was found to 
be slight, and although the affidavit of the manager of the company 
stated that 24 pounds per cubic foot had been injected, upon submitting 
samples to two chemists, one sample was reported to have 4.8 pounds 
per cubic foot and another sample, which was one of the best penetrated 
of the piles, contained only 10 pounds per cubic foot. The analyses also 
determined that the oil was inferior. Judging from the samples taken, it 
became apparent that the piles did not contain the necessary amount of 
oil, notwithstanding that the records of the company showed the treat- 
ment and the amount of oil received by each charge as being sufficient to 
supply an average of 24 pounds per cubic foot in the timber treated. 

The question as to whether the oil was too light and diluted with 
water or was lost through some carelessness, leaks, open valves, or 
whether the reports from subordinates of the company w^ere incorrect, is 
still to a certain extent an open one. Whatever the causes, the fact 
remains that the piles did not receive the amount of good creosote oil 
specified. If they did receive the required weight of the mixture furnished 
as creosote, the oil was so volatile that more than 50 per cent of it dis- 
appeared during the course of from three to six months' exposure. This 



22 

last supposition can not be accepted, for reasons that to my mind are 
conclusive, and I was forced to decide that the treatment was deficient. 

The company desired to furnish other piles to replace those rejected 
and wanted to use the same oil which had been reported on adversely by 
the chemist employed by the Government, still claiming that the oil was 
''a good oil." To illustrate the difficulty of determining whether it was a 
good oil or not, the following is submitted : 

''Analyses made by chemist of 'Wholesale Dealer:' 

Specific gravity 1. 033 

Per cent. 

___° C. to 170" C .7 

170 to 210 '- .5 

210 to 235 24.3 

235 to 270 40.0 

Over 315' C 18.2 

99.9 

Naphthalene ,-__ 23.5 

Tar acids phenols 7.5 

(Apparatus not indicated. Position of bulb of thermometer not known.) 

"The presence of considerable amount of tar acids indicates origin of 
this oil from coal tar." 

"Analysis by chemist of 'Creosoting Company :' 

Specific gravity at 35 C 1.03 

Distillates. ' Percent. 

0' C. to 170° C .5 

170 to 210 6.5 

210 to 240 50.5 

240 to 350 26.0 

Residue above 350° C. 16.0 

99.5 
(Position of thermometer bulb not known. Apparatus not indicated.) 

Samples of two piles from the same lot and supposed to be from the 
same charge and impregnated with the oil in question were forwarded to two 
chemists of national reputation in this line. The piles had been exposed 
to atmospheric conditions about six moriths. 

" Report of first chemist on Sample A : 

Distillates. Percent. 

1. __ ° C. to 170 C 

2.170 to 205 

3.205 to 245 21.27 

4.245 to 270 16.49 

5.270 to 320 18.41 

6.320 to 420 21.18 

7. Above 420 22.31 

99.66 



23 

''From distillate No. 3, 11.06 per cent solid naphthalene was recovered. 
All other distillates were liquid on cooling, proving the absence of anthra- 
cence oil. 

''Amount of anhydrous oil per cubic foot of timber, 4.79 pounds. 
(Should have had 24 pounds.) 

"The entire absence of anthracene oil in the higher fractions, together 
with peculiar appearance of the latter, indicates that the oil used was not 
a straight creosote oil or dead oil of coal tar. 

''A mixture of creosote oil rich in naphthalene, together with a heavy 
oil from water gas tar or a heavy oil from water gas tar to which sludge 
naphthalene had been added, would form a mixture similar to this oil." 

Thermometer bulb at outlet tube of distilling flask, and not touching 
the oil. 

'' Report of second chemist on Sample A : 

Per cent. 

Below 210 C. 0.5 

210' C. to 235' C 2.3 

235 to 270 37.2 

270 to 315 21.8 

Residue 38.2 

"Amount of oil in pile, 3 pounds per cubic foot. 

"The oil is a pure product of coal-tar distillation and as now in the pile 
is a high-grade quality of coal-tar creosote. 

"We estimate the loss during exposure approximates 40 per cent to 50 
per cent." 

After correspondence this chemist acknowledged that he did not consider 
the oil as originally injected as a good oil, but after the water and light oils 
had evaporated it was a good oil. 

" Report of first chemist on Sample B : 

-^. .,, Per cent by 

Distillates. -weight. 

___' C. to 170' C 

170 to 205 

205 to 245 - 28.32 

245 to 270 21.71 

270 to 320 9.04 

320 to 420 17.79 

Residue 22.93 

99.79 

"From distillate No. 3, 21.49 per cent solid naphthalene was recovered. 
No anthracene oil present. 

"This sample had 10.04 pounds per cubic foot." 

Same method as for Sample A by first chemist. 

No report was received from second chemist on Sample B. 

Attention is invited to Figs. 2 and 3 as showing differences, according to 
various reports. 



24 



The question at once arises as to how to explain the divergence of these 
various analyses. It will be noted that the analyses of the wholesale 
dealer and the company using the oil, taken from samples before there 
was much possibility of the oil becoming diluted or adulterated, agree 
fairly well, and such divergence as is shown may be readily explained by 
the fact that the samples were taken from different parts of the storage 
tank and possibly different methods of analysis used. This oil was an 




24-0' 2SO' S80' 

Fig. 2. Curves showing the divergence of analyses of the same oil by different 
chemists, also comparison with the limits of Grade "A" recommended by the 
Forest Service. Full line, analysis furnished by wholesale company. Broken line, 
analysis made for treating company. 

American oil, very thin, and rich in naphthalene. It was, in my opinion, 
a very poor oil to start with, and further investigation discovered that the 
chemical constituents varied very greatly from the bottom of the tank 
towards the top; particularly later, when the oil became diluted with water 
and possibly with other materials, there was a great difference between the 
sample taken from near the top and another from near the bottom. 

Kurthermore, this oil was brought to the plant in a tank steamer that 
had been carrying crude petroleum, and it is possible that some crude 



25 

petroleum had been left in the tank of the steamer. There is no telHng 
how much there was left, but our analyses show that it is probable that 
the oil was mixed with petroleum in this wa.y. When this oil was pumped 
into the storage tank, there was some German oil in the bottom of the 
tanks. 

When we come to the analyses of the oil taken from the samples of 
piles in question, it will be seen that the analyses by the same chemist of 
the two different samples vary greatly. The different amount absorbed 
during treatment, owing to different positions in the charge, may account 
partly for this, and the varying specific gravities of the ingredients of the 
mixture may account for part. There was much water in the oil, prob- 
ably at least 15 per cent, much very light oil and, of course, some heavy oil. 

When a mixture like this enters the treating cylinder, it is natural that 
the heavy oil should settle very rapidly to the bottom and the lighter oil 
and water to the top. Because of this and the difference in absorption 
that may take place, the piles of the same charge would receive different 
amounts and also oils of different specific gravity. Consequently it is not 
difficult to explain the discrepancy in the quantities of the distillates of oil 
from the two samples, if we assume a great length of time for filling tank 
and a very poor oil used that was mixed with water and perhaps other oils 
or saps. An examination of the piles leads to the conclusion that such 
assumption is correct. 

When we compare, however, the analyses of the oils extracted from the 
Sample No. 1 by two different chemists, a remarkable difference is shown. 
One chemist found 3 pounds per cubic foot and the other 4.79 pounds per 
cubic foot. This again might be explained in part by the fact that, of 
course, one sample was nearer the end of the pile than the other. As the 
sample sent each chemist was 3 feet long, if one part was very near the 
end a considerable difference in the amount of oil injected might be found. 
But no explanation occurs to me to account for the discrepancy in the 
amount of the distillates or in the final conclusions by the two chemists, 
except that chemists are not yet able to obtain accurate results by the 
methods in use. 

The chemist who found 4.79 pounds per cubic foot did not know the 
name of the creosoting company using this oil nor did he know, unless by 
surmise, that there was any conflict between the parties to the contract. 
The second chemist furnished said analysis for the creosoting company and 
was aware of the conflict between the parties to the contract and was hired 
and paid by the contracting company. If it were not for the fact that the 
chemist in question is a man of national reputation, it would almost look 
as if he had allowed himself to be affected by his retainer; but I can not 



26 



believe that this is the case, and we must look for the explanation in the 
different methods and apparatus used and to the fact that knowledge of the 
constituents and their proportions in creosote oils, as compared with those 
derived from other oils or other methods, is not at all accurate and seems 
to be limited. 

Again, what are we to think of an oil that is reduced 40 per cent to 
50 per cent by volatilization during from three or six months? The fact 
that the piles were almost as dry as seasoned timber after three months. 



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Fig. 3. Curves showing analyses by different chemists of the same oil as in Fig. 1 
after three months' exposure in the pile. Comparison with the limits of Grade "A" 
as recommended by the Forest Service. Full line "^," analysis made for United 
States Engineer. Broken line, analysis of oil from the same pile made for treating 
company. Full line "!B," analysis made for United States Engineer of oil from 
another pile of the same lot by the same chemist as "A." 

and could be handled without soiling the hands, leads to the conclusion 
that the oil was undoubtedly a very poor oil, containing a large proportion 
of water and probably some crude petroleum, some sap and resin and a 
large proportion of low-boiling oils. But it is impossible for me to believe 
that 40 per cent to 50 per cent of true creosote oil, even with a large 
percentage of water, evaporated in that time. It will, however, be noted 
that there was no distillate below 200° C. found in the timber bv either 



27 

chemist. This would seem to show again that only the high-boihng oils 
are valuable. 

The piles in question having been rejected, the question of oil was again 
taken up with the company, A sample of the oil proposed to be used 
when analyzed showed : 

''Thermometer bulb at mouth of outlet tube. 

Distillates. ^Zlgh!.'" 

1. ___' C. to 170' C. '0.85 

2.170 to 205 6.59 

3.205 to 245 53.99 

4.245 to 270 13.05 

5.270 to 320 12.74 

6.320 to 360 8.23 

7. Residue above 360° C 4.95 

100.40 
''Small amount of pitch. 
"Specific gravity, 1.038 at 15° C. 
'' Water, 0.38 per cent. 

"41.46 per cent solid naphthalene recovered from distillate No. 3. 
"One-fourth of No. 5 and whole of No. 6 solidified on cooling on 
account of anthracene present. 

"Oil contains no impurities; fairly good quality." 

This sample was taken by an employee of the creosoting company from 
the storage tank, evidently from the bottom ; and there is a suspicion that 
the sample may have lost some water and low-boiling oils before being 
analyzed. At any rate, it evidently was not a fair sample, because after 
the oil had been brought to the operating plant, put in the storage tanks 
there and run through the various pipes, etc., a sample of this oil, taken 
by a Government inspector, was sealed and sent to the Department of 
Forestry for analysis, with the following result : 

'Thermometer bulb same as above. 

Specific gravity, 1.0230 at 50' C. 

Water content 12.7 

Distillates. Percent. 

1. ___' C. to 170' C. 5.5 

2.170 to 205 9.7 

3.205 to 255 44.3 

4.255 to 295 11.1 

5.295 to 305 2.9 

6. 305 to above 13.3 

7. Loss gas, etc .5 

100.0 

"Sulphonative residue of 7.8 per cent was found in fraction 285 to 295. 
This residue had a very low index of refraction, and its gravity was much 
lighter than water. The low physical constants and the sulphonation 



28 



residue places this oil in Grade D. The water content is, however, too 
high to admit of even this grading. It is probably a mixture obtained by 
the distillation of the coal and oil tars." 

Attention is invited to Fig. 4, as showing graphically the divergence of 
these analyses. 



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Fig. 4. Curves showing divergence of analyses o' samples taken from the same 
oil. Comparison with the limits of Grade "A" as recommended by the Forest 
Service, same method. Full line, sample taken from storage tank before use. 
"Broken line, sample taken from cylinder during treatment. 

While waiting for the above analysis, the United States inspector at the 
plant took one sample from the storage tanks on the dock from which the 
sample sent to the Forest Service was supposed to have been taken, and 
one from the supply tanks at the plant after the oil was transferred from 
the dock to the plant. These samples were analyzed for water and oils 
distilling off below 170° C. with the following results: 

Sample from tanks on wharf: Percent. 

Showed water 8.66 

Oil distilling off below 170" C 3.66 

Total 12.32 



29 
"Sample from supply tank at works: 

Per cent. 

Water 21.20 

Oil distilling off below 170° C 6.30 

Total - 27.50 

The oil was rejected, as they were unable to free the oil of water. 

Here again we find a vast discrepancy shown by the analyses. There 
is no doubt that the samples were taken from a supply of oil pumped into 
the storage tanks at one time from one vessel, and the only way to account 
for the discrepancies is that the first sample taken by the company was 
taken from the bottom of the storage tank after the oil had been undis- 
turbed for a long time and had had time to arrange itself in layers according 
to the specific gravity of the various ingredients. The Government 
inspector stated that the oil at the bottom of these tanks before warming 
was practically solid. The light oils and a quantity of water which was 
mixed with the oil, or was possibly on top of the oil, was carried to the 
operating plant and was there evidently mixed with oil, water, sap and 
resin in the pipes and the tanks at the plant. 

From the above experience it is very evident that the oil question is a 
very serious one. First: To determine the kind of oil required. Second: 
To see that an oil that complies with the specifications is used. In my 
opinion, the oil to be specified, where heavy charges for marine work are 
required, should be a heavy, high-boiling oil, with a very small percentage 
distilling over below 210° C, and with practically no water therein. If an 
oil could be obtained with no oils distilling below 210° C, I would specify 
such, but I believe that is impossible at the present time unless a special 
oil is prepared for a particular job. When an oil is specified, the greatest 
care on the part of the inspector at the works will be necessary to make 
sure that such an oil is being used. The samples taken for analyses 
should be taken from different parts of the tank and their contents averaged, 
or the samples should be taken from different parts and mixed before the 
analysis is made. Even then you can not be sure that the oil that is 
actually being used has not received water or other adulterants between 
the time the oil is analyzed and used, and the inspector should be com- 
petent to make analyses while the work is being performed, taking the oil 
from the side of the treating cylinder while the work is actually being 
done and the oil is being forced into the piles. 

The following tabulated list shows different treatments given to timber 
during the past six months for construction works under my charge w^ith 
two additional cases that came directly under my close observation. It 
will be noted that there is no uniformity of practice, the treatment varying 
materially at each plant. 



30 



Report of Treatments and Comparison of Results. 





Nature 


Material. 


Steaming. 


Vacuum. 


Oil. 


Total 
time. 




Plant. 






1 










Remarks. 








Hours. 


Max. 
press. 


Hrs. 


nches 


Hrs. 


Max. 
pressure. 


Temp. 


Hours. 






Lbs. 






Lbs 








Lbs. 


°F. 






Santa Fe- 






\ 3 


45 


2 


21-24 


4-8 


175-200 




38-42 


Piling for Bolivar 


24 


Green loblolly 


)\\ 


40 

35 














wharf ; average 
treatment; pene- 


Somerville 




































tration thorough; 
























timber slightly 
























burned. 


Do. 


24 


Partly season- 


(14 


40 


2 


21-24 


4-8 


175-200 




35-39 


Do. 


ed loblolly. 
Seasoned lob- 


)l5 


35 
















Do. 


24 


20 


35 


"2" 


21-24 


7-8' 


'llB-Yo'o 


I.I.IZ 


"2"6'-30' 


Do. 






lolly. 




















Beaumont- 


24 


Green short- 
leaf and lob- 
lolly. 


28 


47 


3 


2\y2 


32 


175 


183 


63 


PilingforU.S. Im- 
migration serv- 
ice, Galveston ; 

^penetration thor- 
ough; excellent. 


Do. 


24 


(Jo 


36 


52 


4 


llVi 


14 


185 


184 


54 


Do. 


Do. 


24 


___do._" 


32 


48 


3/2 


22 


36 


190 


181 


695^ 


Do. 


Galveston. 


24 


Loblolly 


20-24 




2 




4-8 






26-34 


Usual record from 






















this plant. 


Do. 


22 


___do ..__ 


15 




2 


19 


4-8 






21-25 


For bathhouse. 
























Galveston; pene- 
tration thorough. 


Do. 


14 


Dry loblolly__ 


5^2 


30 


1 


17 


V'Z 


40 


135 


7 


For U. S. Engi- 
neers, Galveston: 
penetration 3 
inches. 


Co. 


24 


Long leaf and 
short leaf- 
green. 


8 


30 


4 


26 


5 


150 




17 


For U. S. Engi- 
neers; penetra- 
tion 1 to 2% in- 
ches; analyses 6 
months later 
showed 3 to 10 
pounds; rejected. 


Do. 


24 


—do. 


10 


40 


4 


26 


2 


140 




16 


Do. 


Do 


24 


—do. 


10 


40 


3 


26 


1014 


150 




235^ 


Do. 


Do. 


24 


Seasoned short 
leaf. 


\sy2 


42 


5 


24 


7% 


170 


"lYs' 


28 


Piling for U. S. 
Engineers; ac- 
cepted; fair; al- 
most thorough 
penetration. 


Do 


24 


Green longleaf 


24 


35 


5 


24 


10 


160 


130 


39 


Do. 


Do. 


24 


_...„......... 


26 


45 


5/2 


24 


12 


150 


130 


43^2 


Piling for U. S. 
Engineers; pene- 
tration 3 inches; 
rejected. 


Slidell 


24 


Green loblolly 


23 


60 


6 


21 K2 


7^3 


168 


190 


37>^ 


Piling for U. S. 
Engineers;excel- 
lent ; thorough 
penetration. 


Do 


24 


Long leaf and 
short leaf- 
green. 


24 


60 


4 


2SV2 


125/3 


175 


190 


405/3 


Piling for U. S. 
Engineers; excel- 
lent ; thorough 
penetration ; act- 
ual injection 25.1 
pounds. 


Do. 


24 


__.do 


24 


60 


sYz 


25 


6 


160 


194 


35 K2 


Piling for U. S. 
Engineers; excel- 
lent ; thorough 
penetration ; act- 
ual injection 27.0 
pounds. 


Galveston. 


24 


Green long leal 


19 


45 


85 
(>0 


20 


10 


no 




2^IS 


Material for U. S. 






heart, 4 ' by 














Immigration Ser- 






10". 


















vice, CJalveston ; 
penetration thor- 
ough ; excellent; 
actual injection 
25.3 pounds. 



31 

CONCLUSIONS. 

For marine work and heavy treatment of 20 or more pounds per cubic 
foot of timber : 

Oil. 

Should be best EngHsh coal-tar creosote oil or its equal without admix- 
ture of other oils or substances not derived from the distillation of coal tar; 
its relative gravity at 60° C. compared to water at the same temperature 
should not be less than 1.04; it should contain not more than 3 per cent 
water, the percentage to be compensated for in computing amount of oil_ 
to be injected; not more than 5 per cent should distil below 210° C. aiid 
not more than 25 per cent below 235° C, when analysis is made by 
Forest Service method (see Circular No. 112); not more than 5 per cent 
tar acids should be allowed in oil ; oil should be at same temperature in 
tanks when measurements are made before and after the operation, or 
shrinkage due to change of temperature should be allowed for; oil should 
be kept hot during treatment, temperature 80° C. recommended. Allow- 
ance should also be made in computations for expansion of treating cylinder 
under pressure. 

Fair Samples for Analysis. 

Oil should be completely liquid when sample is taken, and if drawn 
from tanks a number of samples at different heights should be taken and 
averaged. If taken while oil is being transferred, a drip sample taken 
from cock in line is desirable. 

Dilution. 

Inspector should watch closely all means of dilution, and make sure 
none has occurred by analyses of oil taken from treating cylinder during 
process of injection. 

Charge. 

Should be uniform as to kind, cross-section, density and moisture content. 

Steaming. 

Duration and intensity of steaming should be left to management of 
plant on account of varying equipment at different plants, varying density, 
etc., of timber from different localities; however, specifications should 
provide that treatment shall not injure fiber of timber, nor impair strength 
appreciably. 

Vacuum. 

Same as for steaming, with the additional requirement that cylinder and 
contents should be kept hot during process by steam coils in cylinder. 



32 

Absorption. 

To do good work a plant should be properly equipped for filling treating 
cylinder quickly to avoid different degrees of absorption, which tends to 
overload some of the charge while the remainder does not receive the 
required amount. 

Pressure. 

Should be continued until gauges show that a little more than the 
computed amount of oil is injected to allow for dripping and release of 
oil while cylinder is being emptied of the surplus oil and for the expansion 
of the cylinder under pressure. The cylinder doors should be opened 
promptly and the charge withdrawn as soon as possible. 

Inspection. 

Specifications should contain clause requiring management of plant to 
furnish the inspector every facility requested by him for measuring timber, 
oil, tanks, cylinders, etc., and for taking and analyzing oil samples as often as 
deemed necessary, including use of laboratory and such apparatus as he 
may require. 

Inspector. 

Should have sufficient knowledge of the chemistry of creosotes and the 
skill to make the necessary analyses, and should study the plant carefully 
to prevent mixing of water, bad oil, etc., left in pipes, tanks, cylinders, etc. 

For light treatment the same considerations should govern as for heavy 
treatment, except that the oil need not be heated to 80° C, the w^ater 
content may be allowed as high as 8 per cent, all to be compensated for, 
and more care must be exercised to obtain uniform absorption in order to 
obtain uniform results. 

I desire to acknowledge indebtedness for information obtained from the 
various publications of the Forest Service relating to this subject, and also 
for the valuable articles with discussions published by the American Rail- 
way Engineering and Maintenance of Way Association, and to other 
available literature bearing upon the subject. 

I am also indebted for valuable assistance to Mr. CM. Davis, United 
States inspector under the Galveston Engineer Office, who was present at 
the plants during the creosotingof the timber supplied under contract with 
that office during the past six months. 



LIBRARY OF CONGRESS 



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019 713 909 2 



UIBRflRV OF CONGRESS 



'0*9 713 909 2 






Hollingjer 

pH 8^ 

MiU Run F03.2193 



